Many common electrical devices use 110 volt, 15 ampere current (or more) electrical power, which can exceed the capacities of standard 15 ampere circuits and convenience outlets. Many of these devices can also use 220 volt power, which permits halving the delivered amperage while maintaining the same power as a 110 volt supply with double the amperage. Further, other devices use only 220 volt power. Representative of devices that can use or must use 220 volt power are, e.g., floor sanders, cappucino machines, and electric vehicle recharging systems.
Most commercial power outlets, however, supply 110 volt power. One way to convert 110 volt power to 220 volt power is to use a transformer, but use of a transformer, while doubling the voltage, halves the current. Thus, no power gain is realized.
Another way to supply 220 volt power is to provide a 220 volt generator. Unfortunately, such generators require the use of a prime mover such as an engine that might emit noxious fumes and undesirable noise. Also, generators are relatively bulky and expensive. These drawbacks render generators unacceptable for many applications.
As recognized by the present invention, a third way to supply 220 volt power is to use a non-transformer adaptor to convert two 110 volt inputs into a single 220 volt output. As recognized herein, such an adaptor would require two extension cords from two separate 110 volt wall sockets to be plugged into respective male connectors of the adaptor. The voltage can then be summed by the adaptor to supply 220 volt power without halving the current.
As still further recognized herein, however, the use of two male connectors can potentially present a risk of shock. More particularly, if one male connector of an adaptor is plugged into an energized extension cord, and the other male connector of the adaptor remains exposed even if only for a short while, e.g., while a person seeks another wall outlet or extension cord for the exposed male connector, the exposed male connector prongs, without the benefit of the principles set forth herein, would be energized and, thus, would represent a shock hazard.
Additionally, the present invention understands that extension cords and/or the commercial power circuits to which the cords are connected might be incorrectly wired, i.e., have reverse polarity, and that such reverse polarity, when detected, ideally should be corrected prior to power conversion.
Fortunately, the present invention recognizes that it is possible to provide a control circuit for a 220V adaptor that ensures that an exposed male connector of the adaptor is safe, even when the other male connector of the adaptor is energized. Also, the present invention recognizes that it is possible to account for an input power source having reverse polarity.
Accordingly, it is an object of the present invention to provide a 110 volt to 220 volt (110V-220V) adaptor that ensures that exposed male connectors of the adaptor do not present a shock hazard. Another object of the present invention is to provide a 110V-220V adaptor that is easy to use and cost-effective to manufacture. Still another object of the present invention is to provide a method and device for rapidly and easily accounting for reverse polarity in an input power supply to a 220V adaptor.